This application relates to hand tools and more particularly to ratcheting wrenches. It relates in particular to unidirectional ratchet wrenches and to ratchet mechanisms therefor.
Reversible ratchet wrenches have been provided with levers located in the head of the wrench to control the direction of ratcheting. However, some applications, e.g., certain torque wrenches, require operation in only one direction. For example, certain torque wrenches may be designed to apply torque in only the clockwise direction.
Unidirectional ratchet wrenches commonly have specialized pawl assemblies, which are different from the pawl assemblies in the reversible form of the ratchet wrench. This entails considerable additional expense in tooling, parts inventory and the like.
Furthermore, while unidirectional ratchet wrenches are designed to operate in only one ratcheting direction and do not have a mechanism for manual selection of ratcheting direction, they sometimes nevertheless will self-reverse under certain operating conditions. This could be harmful to the ratchet wrench, and, if the wrench is a torque wrench, could be harmful to the torque sensing mechanism. It could also be harmful to the operator and, at the very least is inconvenient, since it often requires disassembly of the ratchet mechanism in order to return the pawl assembly to its intended operating position.
Furthermore, if a unidirectional wrench tends to try to self-reverse, even while it may not reach the reverse operating condition, it may stop in a neutral position in which the pawl cannot engage the ratchet gear at all. This renders the wrench useless and again, typically requires disassembly of the ratchet mechanism in order to correct the problem.
The new and improved wrench of the present application in an embodiment provides for a ratchet wrench comprising a head having a drive member, a rotatable gear disposed in the head and having gear teeth, a pawl disposed in the head in an operating condition in which the pawl is pivotally engageable with the gear to allow torque-applied loading of the gear with the head in a first direction and ratcheting rotation of the head relative to the gear in an opposite direction and an obstruction disposed within the head for engagement with the pawl to prevent the pawl from moving from its operating condition.
The wrench in an embodiment includes a pawl that includes a cam surface having a shape that permits the pawl to be biased to a first pawl operating condition accommodating torque application when the wrench is rotated in one direction and ratcheting operation when the wrench is rotated in the opposite direction. The wrench in an embodiment provides for the pawl to be prevented from moving from the first operating condition by the obstruction abutting the cam surface. The pawl in an embodiment includes teeth which are engageable with the gear teeth of the rotatable gear, the obstruction not interfering with the normal unidirectional ratcheting operation.
The wrench in an embodiment provides an obstruction that prevents self-reversal of the pawl. The wrench in an embodiment provides a pawl that includes inoperative teeth which are prevented from engaging the gear by the obstruction. The wrench in an embodiment provides an obstruction that is a pin formed of a hard metallic material. The wrench in an embodiment provides a pawl that includes a pair of cam surfaces and teeth to engage gear teeth of the gear. The wrench in an embodiment provides a first cam surface that engages the obstruction when the pawl is rotated in the first direction for limiting such rotation. The wrench in an embodiment provides a second cam surface that engages a biasing mechanism to accommodate ratcheting oscillation of the pawl.
The present application in an embodiment also provides for a unidirectional ratchet assembly comprising a rotatable gear having ratchet teeth, a pivotable pawl movable to an operative pawl position allowing for ratcheting rotation of the gear in a first direction and a non-reversing means disposed to interfere with the movement of the pawl to prevent the pawl from being moved to a non-operative pawl position and to prevent rotation of the gear in a second direction. The assembly in an embodiment provides a non-reversing means that comprises an obstruction provided adjacent to the pawl and wherein the obstruction engages a cam surface of the pawl in order to prevent rotation to the non-operative pawl position.
The present application in an embodiment also provides for a method of converting a reversible ratchet wrench to a non-reversible ratchet wrench comprising the steps of providing a wrench having a handle and a head on the handle, providing a rotating gear disposed in the head, providing a pawl initially rotatable between a first pawl position allowing for ratcheting rotation of the gear past the pawl in a first direction and a second pawl position allowing for ratcheting rotation of the gear past the pawl in a second direction and inserting an obstruction member within the head in order to prevent the rotation of the pawl to the second pawl position.
The conversion method in an embodiment provides a pawl that includes engagement teeth and inoperative teeth. The conversion method in an embodiment provides an obstruction member that includes a pin and further comprising the step of locating the pin within the head in order to prevent the pawl from rotating to the second pawl position and maintaining the engagement teeth of the pawl in engagement with the gear. The conversion method in an embodiment further comprises the step of locating the pin within the head to prevent the pawl from rotating to the second pawl position in order to prevent the inoperative teeth of the pawl from engaging the gear. The conversion method in an embodiment comprises the further step of locating the pin within the head to prevent the pawl from rotating to an intermediate pawl position in which the gear could rotate freely in either direction.
The unidirectional ratchet wrench consists of certain novel features and a combination of parts hereinafter described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the unidirectional wrench.